Fruit Phenology of Two Hazelnut Cultivars and Incidence of Damage by Halyomorpha halys in Treated and Untreated Hazel Groves

Over the past decade, Halyomorpha halys has become one of the main threats to hazelnutproduction. Its trophic activity makes kernels inedible due to strongly detrimental effects on theorganoleptic quality. Its management in Italy is still tricky due to the lack of effective native biocontrolagents and authorized and effective insecticides. A field test was performed on San Giovanni (SG)and Tonda Romana (TR) cultivars (early and late ripening, respectively) to assess the intensity ofcimiciato damage with different pest management approaches (no insecticide and integrated pestmanagement, IPM). Moreover, phenological analysis of fruits and the monitoring of stink bug speciesby traps and plant beating were carried out. In the untreated plots, the SG cv showed a highercimiciato incidence with respect to the late TR cv (40% SG-NI vs. 23% TR-NI). This was probablydue to the different phenological phases in which stink bugs injured the fruits. In fact, stink bugbites provoke different kinds of injuries (blanks, shriveled, and cimiciato) according to the fruit'sdevelopment period. Indeed, in the period of highest insect occurrence in the field, the fruits ofthe early cv (SG) were in kernel expansion, a phenological phase in which bug injuries are morelikely in cimiciato defects. Lastly, the IPM did not provide sufficient fruit protection (19% SG-IPM vs.11% TR-IPM). The interaction between the phenological development of hazelnuts and the brownmarmorated stink bug represents a critical aspect in understanding and implementing effectivestrategies for controlling this key pest on hazelnut trees.